1. Field of the Invention
This invention generally relates to semiconductor device fabrication and more particularly to systems for processing a semiconductor wafer.
2. Description of the Related Art
Specialized wafer processing systems are used to process semiconductor wafers into electronic devices. In most wafer processing systems, a carrier containing wafers is loaded into a loading station and transferred to a loadlock. Subsequently, a robot picks up a wafer from the carrier and moves the wafer into a reactor. The wafer is processed in the reactor according to a recipe. Once the wafer has been processed, the robot picks up and transfers the wafer back to the carrier in the loadlock. The carrier is then moved out of the loadlock and back into the loading station.
Gate valves are routinely employed in a variety of circumstances where wafers are moved from an area at a first pressure to an area at a different, second pressure. In general, the gate valve is a device which is used to isolate operational areas in a wafer processing environment, such that the internal pressures within the operational areas can be varied. The gate valve also reduces particulate contamination between operational areas, which may otherwise be problematic to certain wafer processes.
Unfortunately, the use of gate valves in the processing system also has drawbacks. For example, gate valves generally include large numbers of exposed joints, bearings, hinges, and the like, which generate particulates whenever the gate valve is actuated. These particulates can deposit on the wafers and interfere with the processing operation. Moreover, such joints are difficult to lubricate in a low pressure environment, where the lubrication fluid quickly vaporizes. In addition, location of the gate valve within the processing system usually increases the size of the system. Typically, the increased size of the system, increases the time and power required to draw a vacuum, as well as increasing the capital costs associated with manufacturing the system.
For these reasons, it would be desirable to provide a wafer processing system which does not require vacuum isolation between operational areas of the processing system.